An object moves along a straight line and is at position A, where its velocity is decreasing in the positive $x$-direction. What is the direction of the net force acting on the object at position A?

• A. In the negative $x$-direction
• B. In the positive $x$-direction
• C. Perpendicular to the $x$-direction
• D. There is no net force acting on the object

Answer: (A)

Verified step by step guidance

1. Recall Newton's Second Law, which states that the net force acting on an object is related to its acceleration by the equation \(\mathbf{F}_{net} = m \mathbf{a}\), where \(m\) is the mass and \(\mathbf{a}\) is the acceleration vector.
2. Understand that acceleration is the rate of change of velocity. Since the velocity is decreasing in the positive \(x\)-direction, the acceleration must be directed opposite to the velocity vector.
3. Because the velocity is along the positive \(x\)-direction and is decreasing, the acceleration points in the negative \(x\)-direction.
4. Since the net force is in the same direction as the acceleration, the net force must also be directed in the negative \(x\)-direction.
5. Therefore, the direction of the net force acting on the object at position A is opposite to the direction of the velocity, which is the negative \(x\)-direction.